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2012-04-29
Coherent phonon dynamics at the martensitic phase transition of Ni_2MnGa
We use time-resolved optical reflectivity to study the laser stimulated dynamics in the magnetic shape memory alloy Ni_2MnGa. We observe two coherent optical phonons, at 1.2 THz in the martensite phase and at 0.7 THz in the pre-martensite phase, which we interpret as a zone-folded acoustic phonon and a heavily damped a...
1204.6463v1
2012-05-02
Emergence of physical properties mapped in a two-component system
Emergence of various properties is mapped in a two-component system from quantum to mesoscale, using Au-Ag alloys. Experiments are designed so that composition is the primary 'interaction' guiding the evolution of properties across 'emergent length scales'. In bulk, Au-Ag form near-ideal solid solutions at all composit...
1205.0488v1
2012-05-24
Structural and hyperfine characterization of σ-phase Fe-Mo alloys
A series of nine samples of \sigma-Fe_{100-x}Mo_x with 44<x<57 were synthesized by a sintering method. The samples were investigated experimentally and theoretically. Using X-ray diffraction techniques structural parameters such as lattice constants, atomic positions within the unit cell and populations of atoms over f...
1205.5413v1
2012-05-30
Type-I superconductivity in ScGa3 and LuGa3 single crystals
We present evidence of type-I superconductivity in single crystals of ScGa3 and LuGa3, from magnetization, specific heat, and resistivity measurements: low critical temperatures Tc = 2.1-2.2 K; field-induced secondto first-order phase transition in the specific heat, critical fields less than 240 Oe; and low Ginzburg-L...
1205.6836v1
2012-07-02
Kinetic cross coupling between non-conserved and conserved fields in phase field models
We present a phase field model for isothermal transformations of two component alloys that includes Onsager kinetic cross coupling between the non-conserved phase field and the conserved concentration field. We also provide the reduction of the phase field model to the corresponding macroscopic description of the free ...
1207.0367v1
2012-07-17
Ultrafast dynamical path for the switching of a ferrimagnet after femtosecond heating
Ultrafast laser-induced magnetic switching in rare earth, transition metal ferrimagnetic alloys has recently been reported to occur by ultrafast heating alone. Using atomistic simulations and a ferrimagnetic Landau-Lifshitz-Bloch formalism, we demonstrate that for switching to occur it is necessary that angular momentu...
1207.4092v2
2012-06-29
On the algorithmic behaviour of complex physical systems
Starting from the idea that the underlying mechanisms driving the observable processes in nature are algorithmic, we exemplify this in two ways: nature works as a computing machine and thus the processes running on it optimize themselves in an intrinsic manner so as to save time. As a first example we will place the em...
1207.5398v1
2012-10-09
Magnetism in La2O3(Fe1-xMnx)2Se2 tuned by Fe/Mn ratio
We report the evolution of structural and magnetic properties in La2O3(Fe1-xMnx)2Se2. Heat capacity and bulk magnetization indicate an increased ferromagnetic component of the long-range magnetic order and possible increased degree of frustration. Atomic disorder on Fe(Mn) sites suppresses the temperature of the long-r...
1210.2711v1
2012-10-12
Minami's estimate: beyond rank one perturbation and monotonicity
In this note we prove Minami's estimate for a class of discrete alloy-type models with a sign-changing single-site potential of finite support. We apply Minami's estimate to prove Poisson statistics for the energy level spacing. Our result is valid for random potentials which are in a certain sense sufficiently close t...
1210.3542v3
2012-10-15
Single-carrier impact ionization favored by a limited band dispersion
A critical requirement for high gain and low noise avalanche photodiodes is the single-carrier avalanche multiplication. We propose that the single-carrier avalanche multiplication can be achieved in materials with a limited width of the conduction or valence band resulting in a restriction of kinetic energy for one of...
1210.4119v1
2012-11-12
Spin lifetime measurements in GaAsBi thin films
Photoluminescence spectroscopy and Hanle effect measurements are used to investigate carrier spin dephasing and recombination times in the semiconductor alloy GaAsBi as a function of temperature and excitation energy. Hanle effect measurements reveal the product of g-factor and effective spin dephasing time (gTs) range...
1211.2711v2
2012-11-30
Spin-dependent optical properties in strained silicon and germanium
We present a comprehensive theory of the circularly polarized luminescence and its dependence on strain in spin-polarized Si and Ge. Symmetries of wavefunctions and interactions are used to derive concise ratios between intensities of the right and left circularly polarized luminescence for each of the dominant phonon-...
1211.7292v1
2012-12-13
On the existence of solutions for a drift-diffusion system arising in corrosion modelling
In this paper, we consider a drift-diffusion system describing the corrosion of an iron based alloy in a nuclear waste repository. In comparison with the classical drift-diffusion system arising in the modeling of semiconductor devices, the originality of the corrosion model lies in the boundary conditions which are of...
1212.3279v1
2013-01-07
Magnetic domain pattern in hierarchically twinned epitaxial Ni-Mn-Ga films
Magnetic shape memory alloys exhibit a hierarchically twinned microstructure, which has been well examined in epitaxial Ni-Mn-Ga films. Here we analyze consequences of this twin within twins microstructure on the magnetic domain pattern. Atomic and magnetic force microscopy are used to probe the correlation between the...
1301.1200v1
2013-01-15
Modified Associate Formalism without Entropy Paradox: Part I. Model Description
A Modified Associate Formalism is proposed for thermodynamic modelling of solution phases. The approach is free from the entropy paradox described by L\"{u}ck et al. (Z. Metallkd. 80 (1989) pp. 270--275). The model is considered in its general form for an arbitrary number of solution components and an arbitrary size of...
1301.3213v1
2013-02-06
Energy spectrum of pseudospin-electron model in the dynamical mean-field theory
The pseudospin-electron model in the case of infinite on-site electron repulsion is investigated. The electron energy spectrum is calculated within the framework of the dynamical mean field theory (DMFT), and the alloy analogy approximation is developed. The effect of the pseudospin-electron interaction, local asymmetr...
1302.1404v1
2013-02-14
Spectra of Random Operators with absolutely continuous Integrated Density of States
The structure of the spectrum of random operators is studied. It is shown that if the density of states measure of some subsets of the spectrum is zero, then these subsets are empty. In particular follows that absolute continuity of the IDS implies singular spectra of ergodic operators is either empty or of positive me...
1302.3296v1
2013-02-20
Grain boundary segregation of C, N and O in hcp titanium from first-principles
It is believed that grain boundary segregation of light interstitials can serve as possible mechanism of thermal stability in commercially pure nanostructured titanium alloys. In this paper, using first-principles calculations, we show that independent segregation of C, N and O atoms at \Sigma 7 high angle grain bounda...
1302.4836v2
2013-02-22
Crystal structure and properties of barium thorate BaThO$_3$ from first principles
The phonon spectrum of cubic BaThO$_3$ with the perovskite structure is calculated from first principles within the density functional theory. The analysis of unstable modes in the phonon spectrum enables to determine the symmetry of all possible distorted phases, calculate their energies, and show that the ground-stat...
1302.5614v1
2013-03-07
Thickness dependence of the degree of spin polarization of the electrical current in permalloy thin films
Spin-polarized electrical transport is investigated in $ Al_{2}O_{3}/Ni_{80}Fe_{20}/Al_{2}O_{3}$ thin films for permalloy thickness between 6 and 20nm. The degree of spin-polarization of the current flowing in the plane of the film is measured through the current induced spin wave Doppler shift. We find that it decreas...
1303.1692v1
2013-03-22
Defects in quasicrystals, revisited I-flips, approximants, phason defects
The recent discovery of metadislocations in some periodic complex metallic alloys and of their 'phason' defects has given a new impetus to the study of QC approximant defects. In this paper we emphasize: 1- that approximants differ from a QC by a suitable density of 'flips' only, one per unit cell in the case of Fibona...
1303.5563v1
2013-06-17
BZT:a soft pseudo-spin glass
In an attempt to understand the origin of relaxor ferroelectricity, it is shown that interesting behaviour of the onset of non-ergodicity and of precursor nanodomains found in first principles simulations of the relaxor alloy $\mathrm {Ba(Zr}_{1-x}\mathrm{Ti}_{x}\mathrm{)O}_3$ can be understood easily by a simple mappi...
1306.4020v3
2013-06-18
Magnetic domain growth in a ferromagnetic Bose-Einstein condensate: Effects of current
Magnetic domain patterns in a ferromagnetic Bose-Einstein condensate (BEC) show different properties depending on the quadratic Zeeman effect and dissipation. Another important factor that affects domain patterns and domain growth is superfluid flow of atoms. Domain growth in a ferromagnetic BEC with negative quadratic...
1306.4129v2
2013-07-16
Band Structure and Effective Masses of ZnMgO
We analyze the influence of the Mg concentration on several important properties of the band structure of ZnMgO alloys in wurtzite structure using ab initio calculations. For this purpose, the band structure for finite concentrations is defined in terms of the Bloch spectral density, which can be calculated within the ...
1307.4306v1
2013-07-17
Phase separation in Fe2CrSi thin films
Thin films of a nominal Fe2CrSi alloy have been deposited by magnetron co-sputtering with various heat treatments on MgO and MgAl2O4 substrates. After heat treatment, the films were found to decompose into a nearly epitaxial Fe3Si film with the D0$_3$ structure and Cr3Si precipitates with the A15 structure. We explain ...
1307.4734v2
2013-08-01
Exchange relaxation as the mechanism of ultrafast spin reorientation in two-sublattice ferrimagnets
In the exchange approximation, an exact solution is obtained for the sublattice magnetizations evolution in a two-sublattice ferrimagnet. Nonlinear regimes of spin dynamics are found that include both the longitudinal and precessional evolution of the sublattice magnetizations, with the account taken of the exchange re...
1308.0203v1
2013-10-03
Effects of non-uniform Mn distribution in (Ga,Mn)As
Resonant in situ photoemission from Mn 3d states in Ga_{1-x}Mn_{x}As is reported for Mn concentrations down to very dilute limit of 0.1 at %. The properties of the peak at the valence-band maximum reveal an effective interaction between Mn 3d states for concentration as low as 2.5 %. Concentration-dependent spectral fe...
1310.0961v1
2013-10-04
Room temperature optical manipulation of nuclear spin polarization in GaAsN
The effect of hyperfine interaction on the room-temperature defect-enabled spin filtering effect in GaNAs alloys is investigated both experimentally and theoretically through a master equation approach based on the hyperfine and Zeeman interaction between electron and nuclear spin of the spin filtering defect. We show ...
1310.1408v2
2013-10-10
Giant nonlinearity in Zero-Gap Semiconductor Superlattices
Using an effective medium approach, we describe how by combining mercury-cadmium-telluride semiconductor alloys with band gap energies of opposite signs it may be possible to design a superlattice where the electrons have isotropic zero-effective mass and a single valley linear energy-momentum dispersion. We demonstrat...
1310.2789v1
2013-10-14
PMN: a minimal induced-moment soft pseudo-spin glass perspective
An argument that relaxor ferroelectricity in the isovalent alloy $\mathrm {Ba(Zr}_{1-x}\mathrm{Ti}_{x})\mathrm{O}_3$ can be understood as an induced moment soft pseudo-spin glass on the B-ions of the $\mathrm{ABO}_{3}$ matrix is extended to the experimentally paradigmic but theoretically more complex heterovalent relax...
1310.3748v3
2013-10-25
Microscopic origin of the relativistic splitting of surface states
Spin-orbit splitting of surface states is analyzed within and beyond the Rashba model using as examples the (111) surfaces of noble metals, Ag2Bi surface alloy, and topological insulator Bi2Se3. The ab initio analysis of relativistic velocity proves the Rashba model to be fundamentally inapplicable to real crystals. Th...
1310.6893v2
2013-11-13
Hysteretic electrical transport in BaTiO$_3$/Ba$_{1-x}$Sr$_x$TiO$_3$/Ge heterostructures
We present electrical transport measurements of heterostructures comprised of BaTiO$_3$ and Ba$_{1-x}$Sr$_x$TiO$_3$ epitaxially grown on Ge. The Sr-alloying imparts compressive strain to the BaTiO$_3$, which enables the thermal expansion mismatch between BaTiO$_3$ and Ge to be overcome to achieve $c$-axis oriented grow...
1311.3281v1
2013-12-05
Magnetic properties of ferromagnetic Pu2Pt3Si5
The structural, magnetic, and thermodynamic properties of a new plutonium based compound, Pu2Pt3Si5, are reported. Single crystals produced by a Sn-flux technique have been analyzed showing a ferromagnetic behavior at 58 K. Pu2Pt3Si5 crystallizes in the U2Co3Si5-type orthorhombic Iabm structure (72) with atomic paramet...
1312.1576v1
2013-12-13
Free carrier absorption in cascade structures due to static scatterers in the in-plane polarization
We report on the computation of the free carrier absorption induced by static scatterers in cascade structures when the electromagnetic wave propagates along the growth axis. We find that a Drude-like tail exists for this polarization. The absorption is found larger than when the wave propagates in the layer plane. Als...
1312.3767v1
2013-12-19
Probing the local environment of two-dimensional ordered vacancy structures in Ga2SeTe2 via aberration-corrected electron microscopy
There has been considerable interest in chalcogenide alloys with high concentrations of native vacancies that lead to properties desirable for thermoelectric and phase-change materials. Recently, vacancy ordering has been identified as the mechanism for metal-insulator transitions observed in GeSb2Te4 and an unexpected...
1312.5387v1
2013-12-21
Atomistic Potentials for Palladium-Silver Hydrides
New EAM potentials for the ternary palladium-silver-hydrogen system are developed by extending a previously developed palladium-hydrogen potential. The ternary potentials accurately capture the heat of mixing and structural properties associated with solid solution alloys of palladium-silver. Stable hydrides are produc...
1312.6316v1
2014-01-06
The DynAlloy Visualizer
We present an extension to the DynAlloy tool to navigate DynAlloy counterexamples: the DynAlloy Visualizer. The user interface mimics the functionality of a programming language debugger. Without this tool, a DynAlloy user is forced to deal with the internals of the Alloy intermediate representation in order to debug a...
1401.0973v1
2014-01-29
Giant Seebeck coefficient in semiconducting single-wall carbon nanotube film
We found a giant Seebeck effect in semiconducting single-wall carbon nanotube (SWCNT) films, which exhibited a performance comparable to that of commercial Bi2Te3 alloys. Carrier doping of semiconducting SWCNT films further improved the thermoelectric performance. These results were reproduced well by first-principles ...
1401.7469v1
2014-02-06
Thermal response of double-layered metal films after ultrashort pulsed laser irradiation: the role of nonthermal electron dynamics
The thermal response of a Cu-Ti double-layered film is investigated after laser irradiation with ultrashort pulses (pulse duration {\tau}p=50fs, 800nm laser wavelength) in submelting conditions by including the influence of nonthermal electrons. A revised two-temperature model is employed to account for the contributio...
1402.1274v1
2014-03-03
Suppression of antiferromagnetic order in low-dopped ceramic samples La_{2-x}Sr_{x}CuO_{4}
Possible influence of spatially inhomogeneous distribution of strontium impurities on the temperature of antiferromagnetic (AFM) ordering in ceramic samples La2-xSrxCuO4 has been revealed.
1403.0456v1
2014-03-24
Two new mathematical models to predict the flow stress at hot deformation
Based on both linear and non-linear estimations of work hardening rate versus strain curves, two mathematical models have been developed to predict the flow curves under hot working conditions up to the peak. The models were tested for a mechanically alloyed Al6063/0.75Al2O3/0.75Y2O3 nanocomposite under different hot f...
1403.5929v1
2014-04-09
Quantum annealing
Brief description on the state of the art of some local optimization methods: Quantum annealing Quantum annealing (also known as alloy, crystallization or tempering) is analogous to simulated annealing but in substitution of thermal activation by quantum tunneling. The class of algorithmic methods for quantum annealing...
1404.2465v1
2014-04-13
Contact melting and the structure of binary eutectic near the eutectic point
Computer simulations of contact melting and associated interfacial phenomena in binary eutectic systems were performed on the basis of the standard phase-field model with miscibility gap in solid state. It is shown that the model predicts the existence of equilibrium three-phase (solid-liquid-solid) states above the eu...
1404.3379v2
2014-07-27
OKMC simulations of Fe-C systems under irradiation: sensitivity studies
This paper continues our previous work on a nanostructural evolution model for Fe-C alloys under irradiation, using Object Kinetic Monte Carlo modeling techniques. We here present a number of sensitivity studies of parameters of the model, such as the carbon content in the material, represented by generic traps for poi...
1407.7225v1
2014-07-31
Electronic structure of non-centrosymmetric superconductors Re24(Nb;Ti)5 by ab initio calculations
Electronic structures of superconducting Re24Nb5 and Re24Ti5 have been calculated employing the full-potential local-orbital method within the density functional theory. The investigations were focused on the influence of the antisymmetric spin-orbit coupling on band structures and Fermi surfaces of these non-centrosym...
1407.8416v1
2014-08-19
Reduction of Dissipative Nonlinear Conductivity of Superconductors by Static and Microwave Magnetic Fields
A theory of dissipative nonlinear conductivity, $\sigma_1(\omega,H)$, of s-wave superconductors under strong electromagnetic fields at low temperatures is proposed. Closed-form expressions for $\sigma_1(H)$ and the surface resistance $R_s(\omega,H)$ are obtained in the nonequilibrium dirty limit for which $\sigma_1(H)$...
1408.4476v1
2014-08-20
Exponential decay of eigenfunctions in a continuous multi-particle Anderson model with sub-exponentially decaying interaction
This short note is a complement to our recent paper [2] where we established strong dynamical localization for a class of multi-particle Anderson models in a Euclidean space with an alloy-type random potential and a sub-exponentially decaying interaction of infinite range. We show that the localized eigenfunctions at l...
1408.4646v1
2014-08-29
Structure and gap of low-$x$ (Ga$_{1-x}$In$_x$)$_2$O$_3$ alloys
We study the electronic and local structural properties of pure and In-substituted $\beta$-Ga$_2$O$_3$ using density functional theory (DFT). Our main result is that the structural energetics of In in Ga$_2$O$_3$ causes most sites to be essentially inaccessible to In substitution, thus reducing the maximum In content i...
1408.6951v1
2014-10-21
Magnetic switching dynamics in a ferrimagnetic two sub-lattice model including ultrafast exchange scattering
We study the heat-induced magnetization dynamics in a toy model of a ferrimagnetic alloy, which includes localized spins antiferromagnetically coupled to an itinerant carrier system with a Stoner gap. We determine the one-particle spin-density matrix including exchange scattering between localized and itinerant bands a...
1410.5745v2
2014-11-01
A Giant, High-frequency Oscillation of Metal Strip Actuator under DC Electric Field
Different from conventional electroactive polymers, here we firstly present a new facile actuator made from aluminum alloy. The high-frequency electrically induced flapping motion was characterized under varied physical factors. This electroactuation results from alternative processes of charge induction and discharge,...
1411.0079v1
2014-11-11
Mn as surfactant for the self-assembling of Al$_x$Ga$_{1-x}$N/GaN layered heterostructures
The structural analysis of GaN and Al$_x$Ga$_{1-x}$N/GaN heterostructures grown by metalorganic vapor phase epitaxy in the presence of Mn reveals how Mn affects the growth process, and in particular the incorporation of Al, the morphology of the surface, and the plastic relaxation of Al$_x$Ga$_{1-x}$N on GaN. Moreover,...
1411.3006v1
2014-11-18
Study of the specific heat for the binary alloy in the CPA+DMFT method
The thermodynamic properties of strongly correlated system with binary type of disorder are investigated using the combination of the coherent potential approximation and dynamical mean-field theory. The specific heat has a peak at small temperatures for the concentrations close to the filling of system. This peak is a...
1411.4775v2
2014-12-17
Revealing the role of orbital magnetism in ultrafast laser-induced demagnetization in multisublattice metallic magnets by terahertz spectroscopy
Simultaneous detection of THz emission and transient magneto-optical response is employed to study ultrafast laser-induced magnetization dynamics in multisublattice magnets NdFeCo and GdFeCo amorphous alloys with in-plane magnetic anisotropy. A satisfactory quantitative agreement between the dynamics revealed with the ...
1412.5396v1
2015-01-28
Material Properties at Low Temperature
From ambient down to cryogenic temperatures, the behaviour of materials changes greatly. Mechanisms leading to variations in electrical, thermal, mechanical, and magnetic properties in pure metals, alloys, and insulators are briefly introduced from a general engineering standpoint. Data sets are provided for materials ...
1501.07100v1
2015-02-02
Electrical and magnetic properties of La$_{0.5}$Rh$_4$Sb$_{12}$ filled skutterudite synthesized at high pressure
A filled skutterudite, La$_{0.5}$Rh$_4$Sb$_{12}$, with a lattice constant of 9.284(2) {\AA} was synthesized using a high-pressure technique. The electrical resistivity showed semiconducting behavior and the energy gap was estimated to be more than 0.08 eV. Magnetic susceptibility measurements indicated temperature-inde...
1502.00337v2
2015-02-05
Study of the Electron Mobility in InAs/GaSb Type II Superlattices at High Temperatures
In this paper, we present a study of the effects of temperature on the electron mobility in InAs/GaSb type-II superlattices (SLs) in which the band structures and wave functions are calculated by solving the K.P Hamiltonian using the numerical Finite Difference method. In the model the dominant scattering mechanisms su...
1502.01453v1
2015-06-04
Near-Field Plasmonic Behavior of Au/Pd Nanocrystals with Pd-Rich Tips
Using nanometer spatial resolution electron-energy loss spectroscopy (EELS), energy dispersive X-ray spectroscopy (EDS), and cathodoluminescence (CL) mapping, we demonstrate that Au alloys containing a poor plasmonic metal (Pd) can nevertheless sustain multiple size-dependent localized surface plasmon resonances and ob...
1506.01650v1
2015-06-09
Convergence of a Finite Volume Scheme for a Corrosion Model
In this paper, we study the numerical approximation of a system of partial dif-ferential equations describing the corrosion of an iron based alloy in a nuclear waste repository. In particular, we are interested in the convergence of a numerical scheme consisting in an implicit Euler scheme in time and a Scharfetter-Gum...
1506.02996v1
2015-07-13
Defect induced structural and thermoelectric properties of Sb2Te3 alloy
Structural and thermoelectric properties of metallic and semiconducting Sb2Te3 are reported. X-Ray diffraction and Raman spectroscopy studies reveal that semiconducting sample have higher defect density. Nature and origin of possible defects are highlighted. Semiconducting Sb2Te3 hosts larger numbers of defects, which ...
1507.03337v1
2015-07-13
Metallic nanoparticles meet Metadynamics
We show how standard Metadynamics coupled with classical Molecular Dynamics can be successfully ap- plied to sample the configurational and free energy space of metallic and bimetallic nanopclusters via the implementation of collective variables related to the pair distance distribution function of the nanoparticle its...
1507.03505v1
2015-07-16
Proximity Effect in Periodic Arrays of Superconducting Nanoislands on Thin Graphite Layer
The regular structure of superconducting nanoislands of alloy W-Ga-C was fabricated on nanothin graphite using focused ion beam. The resistance vs temperature dependence down to 1.7K and the magnetoresistance in field up to 24T were measured both for the bridge containing nanoislands and for the reference bridge withou...
1507.04584v1
2015-12-14
Superconductivity in the Niobium-rich compound Nb5Se4
The niobium rich selenide compound Nb5Se4 was synthesized at ambient pressure by high-temperature solid-state reaction in a sealed Ta tube. Resistivity and heat capacity measurements reveal that this compound is superconducting, with a T_c = 1.85K. The electronic contribution to the specific heat {\gamma} and the Debye...
1512.04144v1
2015-12-25
Ellipsometry studies of Si/Ge superlattices with embedded Ge dots
In this paper, we present an analysis for treating the spectroscopic ellipsometry response of Si/Ge superlattices (SL) with embedded Ge dots. Spectroscopic ellipsometry (SE) measurement at room temperature was used to investigate optical and electronic properties of Si/Ge SL which were grown on silicon (Si) wafers havi...
1512.07994v1
2016-01-08
A survey of ab-initio calculations shows that segregation-induced grain boundary embrittlement is predicted by bond-breaking arguments
The segregation of solute atoms to grain boundaries can have a large influence on the mechanical behavior of polycrystals, particularly in metallic alloys. An overview of 400 calculations of solute-induced changes in grain boundary cohesion from 77 separate studies quantitatively demonstrates that the majority of the v...
1601.01759v1
2016-01-19
On the photoinduced phase transition in (GeTe)n(Sb2Te3)m
We suggest a phenomenological description of the photo-conversion in Ge-Sb-Te phase-change memory alloys from amorphous to crystalline phase which explains why both photo-excitation and high temperatures T > 160C are required for the transition from hexagonal to tetrahedral phase. The position of chemical potential at ...
1601.04982v1
2016-01-31
Application of the Mössbauer spectroscopy to study harmonically modulated electronic structures: case study of charge- and spin-density waves in Cr and its alloys
Relevance of the M\"ossbauer spectroscopy in the study of harmonically modulated electronic structures i.e. spin-density waves (SDWs) and charge-density waves (CDWs) is presented and discussed. First, the effect of various parameters pertinent to the SDWs and CDWs is outlined on simulated 119Sn spectra and distribution...
1602.00272v1
2016-02-18
Metallic Nickel Silicides: Experiments and Theory for NiSi and First Principles Calculations for Other Phases
We report detailed experimental investigation of the transport and magnetic properties of orthorhombic NiSi along with first principles studies of this phase and related nickel silicides. Neutron scattering shows no evidence for magnetism, in agreement with first principles calculations. Comparison of first principles ...
1602.05840v1
2016-02-23
Phonon Unfolding: A program for unfolding phonon dispersions of materials
We present Phonon Unfolding, a Fortran90 program for unfolding phonon dispersions. It unfolds phonon dispersions by using a generalized projection algorithm, which can be used to any kind of atomic systems in principle. Thus our present program provides a very useful tool for the phonon dispersion and vibration mode an...
1602.07030v1
2016-02-26
Microscopic mechanism of the giant magnetocaloric effect in MnCoGe alloys probed by XMCD
One important aspect of the magneto-structural transition in MnCoGe and related materials is the reduction in saturation magnetization from the orthorhombic to the hexagonal phase. Here, by combining an element specific magnetization probe such as x-ray magnetic circular dichroism and band structure calculations, we sh...
1602.08263v1
2016-05-09
Nanoassembly of Polydisperse Photonic Crystals based on Binary and Ternary Polymer Opal Alloys
Ordered binary and ternary photonic crystals, composed of different sized polymer-composite spheres with diameter ratios up to 120%, are generated using bending induced oscillatory shearing (BIOS). This viscoelastic system creates polydisperse equilibrium structures, producing mixed opaline colored films with greatly r...
1605.02676v1
2016-05-12
Transmission of spin waves in ordered FeRh epitaxial thin films
We report on B2-ordering dependence of magnetostatic surface spin waves in ferromagnetic FeRh at room temperature. Spin waves transmit over a distance longer than 21 {\mu}m in highly ordered FeRh alloys even with relatively large spin-orbit interaction. The long-range transmission likely arises from the induced Rh mome...
1605.03798v1
2016-06-21
Experimental evidence of effective <111> atomic exchanges in a B2 intermetallic alloy
We report on an atomic-scale X-ray Photon Correlation Spectroscopy study on Fe-rich FeAl in the B2-ordered regime revealing effective <111>-exchanges of atoms on the Al-sublattice. The diffusion mechanism responsible for these exchanges is the dominating process for chemical diffusion and therefore controls long-range ...
1606.06516v2
2016-08-03
On the role of Sm in solidification of Al-Sm metallic glasses
During the solidification of Al-Sm metallic glasses the evolution of the supercooled liquid atomic structure has been identified with an increasing population of icosahedral-like clusters with increasing Sm concentration. These clusters exhibit slower kinetics compared to the remaining clusters in the liquid leading to...
1608.01226v1
2016-10-14
DC Magnetization study of Ni$_{1-x}$Rh$_x$ nanoalloy
Ni$_{1-x}$Rh$_x$ bulk alloys exhibit a ferromagnetic to paramagnetic quantum phase transition (QPT) at the critical concentration $x_c \sim$ 0.37. A spin glass phase arises below the Ferromagnetism by controlling the short range interaction between Ni and Rh atoms. we have synthesized nanoalloys of two different concen...
1610.04487v1
2016-11-28
A new class of half-metallic ferromagnets from first principles
Half-metallic ferromagnetism (HMFM) occurs rarely in materials and yet offers great potential for spintronic devices. Recent experiments suggest a class of compounds with the `ThCr$_{2}$Si$_{2}$' (122) structure -- isostructural and containing elements common with Fe pnictide-based superconductors -- can exhibit HMFM. ...
1611.09422v2
2017-01-01
Electrical Transport of perpendicularly magnetized L10-MnGa and MnAl films
Ferromagnetic films of L10-ordered MnGa and MnAl that exhibit giant perpendicular magnetic anisotropy and great controllability in the magnetism and structural disorders show promise not only in the applications in magnetic recording, permanent magnets and spintronics, but also in controllable studies of disorder-relev...
1701.00191v1
2017-03-03
Spin-orbit effective fields in Pt/GdFeCo bilayers
In the increasing interests on spin-orbit torque (SOT) with various magnetic materials, we investigated SOT in rare earth-transition metal ferrimagnetic alloys. The harmonic Hall measurements were performed in Pt/GdFeCo bilayers to quantify the effective fields resulting from the SOT. It is found that the damping-like ...
1703.00995v1
2017-03-27
Gamma relaxation in bulk metallic glasses
Studying the primary {\alpha}- and secondary {\beta}-relaxation process has contributed significantly to the understanding of the structure and rheology of metallic glasses. In this letter, we report on a third relaxation mechanism indicated by a maximum in the loss modulus at low temperatures, which we term {\gamma}-r...
1703.09016v1
2017-07-14
Effect of particle size and inter-particle spacing on dislocation behaviour of Nickel based super alloys
Ni-based superalloys have been the subject of enormous usage in scenarios where the loading is heavy and often occurs at elevated temperatures. The strengthening mechanisms that come into play within the metallic lattice have been studied extensively as micromechanical MMC models. These continuum formulations suffer fr...
1707.04398v1
2017-08-30
Two-dimensional Rashba metals: unconventional low-temperature transport properties
Rashba spin-orbit coupling emerges in materials lacking of structural inversion symmetry, such as heterostructures, quantum wells, surface alloys and polar materials, just to mention few examples. It yields a coupling between the spin and momentum of electrons formally identical to that arising from the weakly-relativi...
1708.09331v1
2017-09-28
Switching of Co magnetization driven by antiferromagnetic-ferromagnetic phase transition of FeRh alloy in Co/FeRh bilayers
We show that Co spins in Co/FeRh epitaxial bilayers grown on W(110) switch reversibly between the two orthogonal in-plane directions as the FeRh layer undergoes temperature driven antiferromagnetic-ferromagnetic (AFM-FM) phase transition. Switching of Co magnetization is characterized by a hysteretic behavior owing to ...
1709.09928v1
2017-12-20
Information entropy of liquid metals
Correlations reduce the configurational entropies of liquids below their ideal gas limits. By means of first principles molecular dynamics simulations, we obtain accurate pair correlation functions of liquid metals, then subtract the mutual information content of these correlations from the ideal gas entropies to predi...
1712.07679v3
2017-12-24
Using Liquid Metal in an Electromechanical Motor with Breathing Mode Motion
Electromechanical actuators exploit the Lorentz force law to convert electrical energy into rotational or linear mechanical energy. In these electromagnetically induced motions, the electrical current flows through wires that are rigid and consequently the types of motion generated are limited. Recent advances in prepa...
1801.01405v1
2018-02-28
Materials data validation and imputation with an artificial neural network
We apply an artificial neural network to model and verify material properties. The neural network algorithm has a unique capability to handle incomplete data sets in both training and predicting, so it can regard properties as inputs allowing it to exploit both composition-property and property-property correlations to...
1803.00133v1
2018-03-03
On the correlation of shear band formation and texture evolution in $α$-brass during accumulative roll bonding
We studied the microstructural evolution of the low stacking fault energy $\alpha$-brass alloy CuZn15 during accumulative roll bonding (ARB). Most notably, the typical brass-type texture was clearly observed after four ARB passes (approx. 93.8 % total thickness reduction), before significant shear localization set in. ...
1803.01251v1
2018-05-14
Additive Manufacturing of Nickel Based Superalloy
This paper reviews the use of relatively new manufacturing method called as additive manufacturing, most often mentioned as 3D printing in fabrication of high performance superalloys. The overview of the article describes the structure, property, processing, performance relationship of the fabrication process and the s...
1805.11664v1
2018-09-06
Thin film superconducting quantum interferometer with ultralow inductance
A simple method has been developed for manufacturing a thin film superconducting quantum interferometer (SQI) with ultralow inductance (~10^-13 H). Current-voltage and voltage-field characteristics of the SQI are presented. The basic design equations are obtained and confirmed experimentally. The SQI has been used for ...
1809.01932v1
2018-09-23
Assessing the Utility of Structure in Amorphous Materials
This paper presents a set of general strategies for the analysis of structure in amorphous materials and a general approach to assessing the utility of a selected structural description. Measures of structural diversity and utility are defined and applied to two model glass forming binary atomic alloys. In addition, a ...
1809.08589v2
2018-11-15
Error and stability analysis of an anisotropic phase-field model for binary-fluid mixtures in the presence of magnetic-field
In this article, we study the error and stability of the proposed numerical scheme in order to solve a two dimensional anisotropic phase-field model with convection and externally applied magnetic field in an isothermal solidification of binary alloys. The proposed numerical scheme is based on mixed finite element meth...
1811.06239v1
2019-11-08
Magnetic i-MXene: a new class of multifunctional two-dimensional materials
Based on density functional theory calculations, we investigated the two-dimensional in-plane ordered MXene (i-MXenes), focusing particularly on the magnetic properties. It is observed that robust two-dimensional magnetism can be achieved by alloying nonmagnetic MXene with magnetic transition metal atoms. Moreover, bot...
1911.03470v1
2019-11-12
Ultrafast synthesis of Pb-doped BiCuSeO oxyselenides by high-energy ball milling
We report on the direct ultrafast synthesis of Pb-doped BiCuSeO oxyselenides by high-energy ball milling. We show that, contrary to the mechanical alloying sintering routes used in the previous reports which require 7 - 13 hours to fabricate the BiCuSeO phase in powder form, this synthesis technique enables us to obtai...
1911.04843v2
2019-11-27
Onset of a skyrmion phase by chemical substitution in MnGe chiral magnet
We study the evolution of the magnetic phase diagram of Mn$_{1-x}$Fe$_{x}$Ge alloys with concentration $x$ ($0 \leq x \leq 0.3$) by small-angle neutron scattering. We unambiguously observe the absence of a skyrmion lattice (or A-phase) in bulk MnGe and its onset under a small Mn/Fe substitution. The A-phase is there en...
1911.12190v1
2017-04-16
Raman study of lattice vibrations in type II superlattice InAs/InAs1-xSbx
In this work, we report a polarized Raman study on the vibrational properties of the InAs/InAs1-xSbx SLs as well as selected InAs1-xSbx alloys, all grown on GaSb substrates by either MBE or MOCVD, from both growth surface and cleaved edge.
1704.04770v1
2017-04-26
Study of the composition dependence of the ionic conductivity of LiH_{x}D_{1-x} alloys
Recent observations have shown that at a certain composition of solid solutions AgCl$_x$Br$_{1-x}$, AgCl-CdCl$_2$, AgBr-CdBr$_2$, of ionic crystals, the electrical conductivity exhibits a value appreciably larger than that of the end constituents. Here, we investigate the electrical conductivity $\sigma$ of LiH$_x$D$_{...
1704.08047v1
2017-04-27
Calculation of the bulk modulus of mixed ionic crystal NH_4Cl_{1-x}Br_x
The ammonium halides present an interesting system for study in view of their polymorphism and the possible internal rotation of the ammonium ion. The static properties of the mixed ionic crystal NH$_4$Cl$_{1-x}$Br$_x$ have been recently investigated, using three-body potential model (TDPM) by the application of Vegard...
1704.08456v1
2017-05-18
Phase Diagram of Carbon Nickel Tungsten: Superatom Model
Carbon solubility in face-centered cubic Ni-W alloys and the phase diagram of C-Ni-W are investigated by means of first principle calculations and semi-grand canonical Monte Carlo simulations. With density functional theory (DFT) total energies as fitting data, we build a superatom model for efficient simulation. Multi...
1705.06641v1
2018-07-15
Improvement of Thermoelectric properties of Lanthanum cobaltate by Sr and Mn co-substitution
We report thermoelectric (TE) properties of Sr and Mn co-substituted LaCoO3 system from room temperature to 700 K. Sr-substitutions at La and Mn at Co site in LaCoO3 improves the electrical conductivity ({\sigma}). Thermal conductivity (\k{appa}) of all the samples increases with the increase in temperature but decreas...
1807.05562v1
2018-07-16
Absence of strong skew scattering in crystals with multi-sheeted Fermi surfaces
We consider an extrinsic contribution to the anomalous and spin Hall effect in dilute alloys based on Fe, Co, Ni, and Pt hosts with different substitutional impurities. It is shown that a strong skew-scattering mechanism is absent in such crystals with multi-sheeted Fermi surfaces. Based on this finding, we conclude on...
1807.05903v1
2018-10-20
On Fractional Annealing Process
The paper deals with a full annealing process, for example for a metal alloy perturbed by some fractional noise caused by conditions in furnace such as initial temperature, initial structure of material itsel. The energy of the heating matter system depending on its states at each time, we consider some steady state at...
1810.09916v1
2018-10-28
Active Learning of Uniformly Accurate Inter-atomic Potentials for Materials Simulation
An active learning procedure called Deep Potential Generator (DP-GEN) is proposed for the construction of accurate and transferable machine learning-based models of the potential energy surface (PES) for the molecular modeling of materials. This procedure consists of three main components: exploration, generation of ac...
1810.11890v2